Fix typo in subprocess documentation.
diff --git a/Doc/library/subprocess.rst b/Doc/library/subprocess.rst
index 6ea3c10..4a12b76 100644
--- a/Doc/library/subprocess.rst
+++ b/Doc/library/subprocess.rst
@@ -387,7 +387,7 @@
:func:`call` and :meth:`Popen.communicate` will raise :exc:`TimeoutExpired` if
the timeout expires before the process exits.
-Exceptions defined in this module all inherit from :ext:`SubprocessError`.
+Exceptions defined in this module all inherit from :exc:`SubprocessError`.
.. versionadded:: 3.3
The :exc:`SubprocessError` base class was added.